Soft-X-ray Magnetic Circular Dichroism under Pulsed High Magnetic Fields at Eu M_{4,5} Edges of Mixed Valence Compound EuNi2(Si0.18Ge0.82)2

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By applying our new experimental technique of X-ray absorption spectroscopy (XAS) and its X-ray magnetic circular dichroism (XMCD) in the soft-X-ray region under high pulsed magnetic fields of up to 21.3 T, we measured the XAS and XMCD spectra at the Eu M_{4,5} edges of EuNi2(Si0.18Ge0.82)2. The measured spectra are analyzed by taking into account the atomic multiplet structures to clarify the mixed valence properties, which are caused by the hybridization between Eu2+ and Eu3+ configurations. We obtain the field dependence of the average valence number from the XAS spectra and that of the magnetizations of Eu2+ and Eu3+ components separately using the spin and orbital sum rules from the XMCD spectra. These results are in good agreement with theoretical ones calculated with a modified single-impurity Anderson model. The present study reveals the key to solving a puzzling problem that was posed in previous XAS and XMCD experiments in the hard-X-ray region.
2012-10-15